Symbols on Weather Maps
Learning Goal 1f. Recognize and interpret certain weather and
obscuration glyphs on weather charts.
Weather maps show locations of weather stations worldwide. Each weather station observes
many
weather variables (wind, temperature, clouds, weather, precipitation, etc).
The
issue: how to display so much info at so many locations on the
same
map? The solution: meteorologists devised symbols or glyphs
as a
short-hand notation for many of these weather variables.
In the tables below, the glyph is the symbol that is used on
weather
maps. Also listed for completeness is the text abbreviation
for
the same phenomenon, which is used in text-based Meteorological Aviation
Reports
(METARs). For this course, focus only on the glyphs.
For this learning goal we consider only a small sample of the glyphs
used in meteorology. There are many more that are not shown here,
and for which you are NOT responsible to know for this course.
Please focus on only the key glyphs shown here.
Weather and Storm Glyphs
The intensity of the
precipitation is indicated by the number and arrangement of those
glyphs, as described in Table 9-3b. Also, a descriptor for
the
precipitation can be included. Here is just a subset of intensity and descriptor glyphs:
Obscuration Glyphs
Examples of Combinations of Glyphs
The glyphs described above can be combined in logical ways. Here are some examples:
Glyphs
|
Meanings
|
|
.
Moderate-intensity drizzle
.
.
Moderate-intensity rain
.
.
Moderate-intensity snow
|
|
.
Rain shower | snow shower
|
|
Thunderstorm with rain | Thunderstorm with snow
|
|
Freezing drizzle | Freezing rain
|
Keywords: drizzle, rain, snow, heavy, light,
moderate, shower, thunderstorm, freezing, fog, haze, mist, smoke, sand, blowing
Extra info for Experts; Not Needed
for this Course.
Explanation of "light", "moderate", and "heavy" precipitation
For rain, the intensity is given by how fast a bucket or
rain gauge fills with rainwater, i.e. the
increase in water depth per hour (e.g. mm/h).
Table 7-3 gives the details.
For drizzle and snow, the intensity is given by how poor the visibility
is. Visibility is how far you can see through the atmosphere,
and
is discussed in Learning Goal 9e. It is measured
as a
distance (e.g. km). Table 7-4 gives the details.
Storm Glyphs
Cloud Glyphs
There are many cloud glyphs, so we will focus on the main ones
here. Refer back to Learning
Goal 9a to see photos of
these
clouds.
.
.
Practice Exercises for Experts (not needed for this Course)
Sample Answers:
Exercise (c) shows the symbol for intermittent moderate
drizzle.
Exercise (s) shows the symbol for a light rain shower.
Exercise (ab) shows the symbol thunderstorm with snow.
While the above tables showed the general principles used to organize
the weather-map symbols, here is a link that shows each specific symbol with an
explanation of what it means.
(Courtesy of the US National Center for
Atmospheric Research. From
http://weather.rap.ucar.edu/info/wxSymbols_anno1.pdf , downloaded on 24
May 2017.)
Other useful links for experts:
NCAR: Comparison
of weather-map symbols with METAR codes.
Stull, 2017: Practical Meteorology (PrMet): Chapter 9. Weather Reports & Map Analysis
World Meteorological Organization (WMO): WMO International Cloud Atlas Manual on the Observation of Clouds and Other Meteors
American Meteorological Society (AMS): Glossary of Meteorology
Stull, 2017: Practical Meteorology (PrMet): Chapter 6. Clouds
Keywords: Meteorological Aviation Report (METAR)
Image credits. All figures by Roland
Stull, except for two from NCAR, as credited at the links to those two
figures.